Optical microphones allow optically detecting human speech related acoustic signals and often rely on facial vibrations for speech detection since optical signals have high sensitivity to vibrating surfaces. However, the output of the optical microphones is of much lower signal quality than that of commonly used acoustic microphones based on transducers that produce electric current upon being vibrated in response to speech related air vibrations.
U.S. Pat. No. 7,775,113 and U.S. application Ser. No. 11/841,134, which are incorporated herein by reference in their entirety, disclose an optical microphone system that includes an optical transmitter and receiver for receiving and transmitting optical signals (beams) for optical detection of speech related acoustic signals by detection of, inter alia, facial vibrations of a relevant speaker. These optical microphones can use techniques such as vibrometry, self-mix and/or interferometry, for instance, for acoustic signals detection.